1. Field of the Invention
The present invention relates to a power control system. More particularly, the present invention relates to a multiple-level power control system.
2. Description of the Related Art
In general, a typical ceiling light or a ceiling fan uses a wall-mounted power switch to provide a basic ON-OFF control. However, most wall-mounted switches in use today are of the single-pole, single-throw type. Therefore, in most existing home lighting systems, a typical wall-mounted switch breaks the current-flow loop at only one of the two alternating current (AC) lines, not both. As shown in FIG. 1, two AC lines 101 (AC1) and 102 (AC2) are intended for providing the utility AC voltage 100 to a ceiling lamp 105. But only AC line 102 is actually wired to the input side of a wall switch 104. The output side of wall switch is connected back to lamp 105 via a return wire 103.
A conventional power switch, such as the wall switch 104, can offer only ON-OFF function. At its ON position, the power switch provides un-impeded current flow; whereas at its OFF position, the power switch disconnects (or isolates) the load (such as lamp 105) from one or both AC lines that provide the utility AC voltage.